The present invention relates to a MEMS component, in the layer structure of which at least one sound-pressure-sensitive diaphragm element is formed, which spans an opening in the layer structure, the diaphragm element being attached via at least one column element in the central area of the opening to the layer structure of the component.
Such a MEMS microphone component is described in PCT Published Application No. WO 2008/103672 A2. The signal detection takes place here capacitively with the aid of a capacitor arrangement, the electrodes of which are situated, on the one hand, on the movable diaphragm element and, on the other hand, on a fixed counter element of the microphone structure. The microphone structure is implemented in a layer structure on a base substrate, so that the diaphragm element and the counter element are situated one above another and spaced apart from one another. The diaphragm element extends over an opening in the substrate rear side. It is connected only to the counter element, specifically by a centrally situated column element. The outer edge of the diaphragm element is not incorporated into the layer structure, so that intrinsic mechanical stresses in the diaphragm element may dissipate via the free diaphragm edge.
The conventional capacitive MEMS microphone component is distinguished by a very good microphone performance, in particular with regard to the signal-to-noise ratio SNR, but in exchange the power consumption in the case of capacitive signal detection is relatively high and is excessively high for an “always-on” operation.
A MEMS microphone component having a sound-pressure-sensitive diaphragm element is described in U.S. Patent Application Pub. No. 2014/0084395 A1, which spans an opening or cavity in the layer structure and the outer edge of which is circumferentially attached to the layer structure of the component. The deflections of the diaphragm element are detected here with the aid of at least one piezosensitive circuit element, which is situated in the edge area of the diaphragm element, i.e., in the area of the attachment of the diaphragm element to the layer structure.
One advantage of piezosensitive MEMS microphone components in relation to capacitive MEMS microphone components is that they may be equipped very easily with a “wake-up” functionality. They may thus be developed in such a way that they only consume power if needed, i.e., for example, only if a specific sound level is exceeded. The power consumption of piezosensitive MEMS microphones in the “always-on” operating mode is thus significantly less than that of capacitive MEMS microphone components.
However, production-related and/or temperature-related mechanical stresses frequently occur within the diaphragm structure in the case of diaphragm elements incorporated circumferentially into the layer structure, as in the case of the MEMS microphone component described in U.S. Patent Application Pub. No. 2014/0084395 A1, these stresses not being able to dissipate due to the circumferential incorporation. Such intrinsic mechanical stresses have a particularly disadvantageous effect on the performance of piezosensitive MEMS microphones, since they directly influence and corrupt the measuring signal.